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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

43111 results found.

  1. GRB 250309B: Swift-XRT refined Analysis
  2. GRB 250309B / IceCube-250309A: GECAM-B observations
  3. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  4. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  5. GRB 250309B / AT2025dws: SAO RAS optical observations
  6. GRB 250309B / AT2025dws: Swift-UVOT detection
  7. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  8. GRB 250309B: Fermi GBM Observation
  9. Fermi GRB 250309B: Global MASTER-Net observations report
  10. Fermi GRB 250309A: Global MASTER-Net observations report
  11. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  12. IceCube-250309A: No candidates from the Zwicky Transient Facility
  13. Fermi-LAT gamma-ray observations of IceCube-250309A
  14. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  15. GRB 250309B: Fermi GBM Final Localization
  16. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  17. GRB 230509B: Tiled Swift observations
  18. GRB 250308A: SVOM/GRM observation of a bright short burst
  19. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  20. IceCube Alert 250309.32: Global MASTER-Net observations report
  21. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  22. EP250308a: Global MASTER-Net observations report
  23. EP250308a: GSP optical upper limit
  24. EP250308a: FTW optical and NIR upper limits
  25. EP250308a: Einstein Probe detection of an X-ray transient
  26. EP250308a: NOT optical upper limit
  27. GRB 250309A: Fermi GBM Final Real-time Localization
  28. GRB 250306A: EIRSAT-1 GMOD detection
  29. The EP-WXT trigger 01709132387 is likely a flaring star
  30. Fermi GRB 250307A: Global MASTER-Net observations report
  31. Konus-Wind detection of GRB 250306A
  32. GRB 250307A: Fermi GBM Final Real-time Localization
  33. GRB 250306A: Swift-BAT refined analysis
  34. GRB 250306A: NuSTAR detection of the prompt emission
  35. EP250304a: MeerKAT detection of a possible radio counterpart
  36. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  37. GRB 250305A: AstroSat CZTI detection
  38. EP250302a:Xinglong optical observations
  39. GRB 250306A: AstroSat CZTI detection
  40. Fermi trigger No 762963055: Global MASTER-Net observations report
  41. Swift GRB 250306A: Global MASTER-Net observations report
  42. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  43. GRB 250306A: Swift detection of a burst
  44. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  45. GRB250101A: Radio upper limits from VLA observations
  46. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  47. GRB 250305A: SVOM/GRM observation of a burst
  48. The EP-WXT trigger 01709132323 is likely a flaring star
  49. EP250304A: Upper limits from Fermi-GBM Observations
  50. Fermi GRB 250305A: Global MASTER-Net observations report
  51. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  52. GRB 250305A: Fermi GBM Final Real-time Localization
  53. EP250302a: Optical Observations at CrAO and SAO RAS
  54. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  55. EP 250304A: Optical counterpart detection by LCO
  56. EP250302A: 1.3m DFOT optical afterglow detection
  57. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  58. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  59. Konus-Wind detection of GRB 250222A
  60. EP250304a: REM NIR upper limits
  61. IPN triangulation of GRB 250222A
  62. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  63. EP250302a: Mondy Continued Optical Observations
  64. EP250304a: VLT/X-shooter redshift z = 0.200
  65. EP250304a: Swift-XRT detection of a fading X-ray source
  66. EP250304a: TRT optical counterpart detection
  67. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  68. EP250304a: Global MASTER-Net observations report
  69. EP250304a: Einstein Probe detection of an X-ray transient
  70. EP250302a: SVOM/VT optical observation
  71. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  72. EP250302a: SAO RAS optical observations
  73. EP250302a : GIT optical follow-up
  74. EP250302a: VLT/X-shooter redshift confirmation
  75. EP250225a: the candidate optical counterpart is an AGN
  76. EP250302a: Kinder optical follow-up observations
  77. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  78. EP250302a: Swift/UVOT detection
  79. EP250302a: NUTTelA-TAO Early Measurments
  80. EP250302a: optical observation from the INAF Asiago Observatory
  81. EP250302a: REM NIR upper limits
  82. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  83. EP250302a: Mondy Observations and Optical Light Curve
  84. EP250302a: VLT/MUSE optical redshift z = 1.131
  85. INTEGRAL: end of scientific operations
  86. EP250302A: VLT near-infrared observations
  87. EP250302A: VLT/X-shooter tentative redshift
  88. EP250302a: OHP/T193 optical and spectroscopic observations
  89. EP250302a: Global MASTER-Net observations report
  90. EP250302a: Xinglong F60B optical observation
  91. EP250302a: Swift-XRT observations of a fading X-ray source
  92. EP250302a: Einstein Probe detection of an X-ray transient
  93. EP250302a: SVOM/C-GFT optical observations
  94. GRB 250226A: GRANDMA Optical Observations
  95. EP250302a: Montarrenti Observatory optical detection
  96. Fermi GRB 250302A: Global MASTER-Net observations report
  97. EP250302a: FTW optical and NIR detection
  98. EP250302a: Nanshan/HMT optical counterpart detection
  99. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  100. GRB 250302A: Fermi GBM Final Real-time Localization

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